As the Gulf oil spill approaches its third month, researchers are using a relatively new tool to track the plume: "glider" robots that use water power to zigzag through the ocean.

Eight of these robots are now prowling the Gulf, driven remotely by researchers from institutions across the country. The gliders carry sensors to measure everything from water temperature to organic material that could mark the presence of dissolved oil.

The idea, said Rutgers University oceanographer Oscar Schofield, one of the collaborators on the effort, is to track the spill and provide data on ocean movement to improve predictions of where the oil will go next.